1. Field of the Invention
The present invention relates to gear assemblies and more particularly pertains to a new variable ratio sprocket assembly for providing improved transition between gears and eliminating derailing.
2. Description of the Prior Art
The use of gear assemblies is known in the prior art. More specifically, gear assemblies heretofore devised and utilized are known to consist basically of familiar, expected and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which have been developed for the fulfillment of countless objectives and requirements.
Known prior art includes U.S. Pat. Nos. 4,850,939; 4,961,719; 3,800,613; 4,740,190; 5,458,543; and U.S. Pat. No. Des. 325,184.
While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not disclose a new variable ratio sprocket assembly. The inventive device includes an axle providing a center for rotation coupled to a frame of the bicycle and designed to rotatably receive the rear bicycle wheel hub, a receiver includes a first diameter coupled to the rear bicycle wheel hub such that rotating the receiver rotates the rear wheel, a converter includes a second diameter substantially greater than the diameter of the receiver and slideably engages the receiver to provide a plurality of gear ratios with respect to the receiver, a driver includes a third diameter substantially greater than the second diameter of the converter and is slideably engaged by the converter such that rotating the driver in a first direction rotates the converter in a first direction which in turn rotates the receiver in a first direction which rotates the rear wheel in a first direction, and a sprocket coupled to an exterior surface of the driver designed for engaging a drive chain which rotates the sprocket.
In these respects, the variable ratio sprocket assembly according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in so doing provides an apparatus primarily developed for the purpose of providing improved transition between gears and eliminating derailing.
In view of the foregoing disadvantages inherent in the known types of gear assemblies now present in the prior art, the present invention provides a new variable ratio sprocket assembly construction wherein the same can be utilized for providing improved transition between gears and eliminating derailing.
The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new variable ratio sprocket assembly apparatus and method which has many of the advantages of the gear assemblies mentioned heretofore and many novel features that result in a new variable ratio sprocket assembly which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art gear assemblies, either alone or in any combination thereof.
To attain this, the present invention generally comprises an axle coupled to a frame of the bicycle providing a center for rotation, a bicycle wheel hub coupled to a rear wheel of the bicycle and designed to rotatably receive force from the sprocket assembly, a receiver includes a first diameter coupled to the bicycle wheel hub such that rotating the receiver rotates the rear wheel, a converter includes a second diameter substantially greater than the diameter of the receiver and slideably engages the receiver to provide a plurality of gear ratios with respect to the receiver, a driver includes a third diameter substantially greater than the second diameter of the converter and is slideably engaged by the converter such that rotating the driver in a first direction rotates the converter in a first direction which in turn rotates the receiver in a first direction which rotates the rear wheel, and a sprocket coupled to an exterior surface of the driver designed for engaging a drive chain which rotates the sprocket.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
It is therefore an object of the present invention to provide a new variable ratio sprocket assembly apparatus and method which has many of the advantages of the gear assemblies mentioned heretofore and many novel features that result in a new variable ratio sprocket assembly which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art gear assemblies, either alone or in any combination thereof.
It is another object of the present invention to provide a new variable ratio sprocket assembly which may be easily and efficiently manufactured and marketed.
It is a further object of the present invention to provide a new variable ratio sprocket assembly which is of a durable and reliable construction.
An even further object of the present invention is to provide a new variable ratio sprocket assembly which is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to the consuming public, thereby making such variable ratio sprocket assembly economically available to the buying public.
Theory of operation
The device consists of Four main components. The first three components consist of: the Driver, the Converter, and the Receiver. The additional label of xe2x80x9cTransmitterxe2x80x9d may be applied to the receiver, as it is the Receiver that transmits torque received from the Driver/Converter assembly to the rear wheel of the bicycle.
The process of delivering power to the rear wheel of the bicycle, and changing gear ratios proceeds as follows.
A standard chain is wrapped around a standard sprocket attached to the pedals of the bicycle, where torque begins. The chain is then wrapped around a second sprocket at the rear of the bicycle; this second sprocket is a structured part of the Driver. The Driver is a disc with a hole in the centerxe2x80x94a hole less-than-equal to the diameter of the Converter, which is also a disc three-quarters the diameter of the Driver. The Converter also has a hole in the centerxe2x80x94a hole less-than-equal to the diameter of the Receiver/Transmitter, which is a disc three-quarters the diameter of the Converter. The Driver and the Converter have a U-shaped cross-section. The Receiver/Transmitter fits inside the Converter, the Converter fits inside the Driver. The device in the first gear ratio is a system of concentric circles. The inner side-walls of the Driver and the Converter contain ridges shaped like stairs. The leading edges of these stair-shaped ridges face forward and begin at the diameter of the hole in the center of both the Driver and the Converter, and the leading edges of these ridges terminate at the outer diameter of both the Driver and the Converter respectively. The form and function of these ridges will be explained in further detail in later paragraphs.
The Converter and the Receiver/Transmitter are equipped with teeth at their outer diameters. These teeth are semi-circle in shape; these teeth protrude from both sides of the Converter and the Receiver and are facing backwards. The backward-facing teeth of the Receiver/Transmitter make contact with the forward-facing leading edges of the stair-shaped ridges on the inner side-walls of the Converter. The backward-facing teeth of the Converter make contact with the forward-facing leading edges of the stair shaped ridges on the inner side-walls of the Driver. The interaction between these teeth and the stair-shaped ridges will be explained in later paragraphs.
Torque from the chain is delivered to the sprocket attached to the Driver; the Driver delivers this torque to the Converter via the stair-shaped ridges on the inner-side walls of the Driver making contact with the teeth structured to the Converter. The Converter delivers this torque to the Receiver via the stair-shaped ridges on the inner side-walls of the Converter making contact with the teeth structured to the Receiver. The Receiver transmits this torque to the rear wheel of the bicycle. The Receiver/Transmitter is attached to the rear wheel of the bicycle, in the standard and conventional method that current sprockets are attached to the rear wheel of a bicycle.
The fourth component of the device is the Hub and Shifter assembly, upon which the Driver and the Converter must rotate on. The Hub assembly is attached to the frame of the bicycle at the rear in line with the axle; the axle of the rear bicycle wheel is inserted through the center of the Hub and attaches to the bicycle frame in the standard and conventional method of current bicycles.
The Hub assembly consists of three main components:
The Driver hub, the Converter hub and the Shifter.
The Driver hub is the main structure that supports the Converter hub and the Shifter. The Driver hub is attached to the bicycle frame; it is primarily flat and has a diameter equal to the hole in the center of the Driver. The one side-wall of the Driver facing away from the bicycle wheel is what contacts the Driver hub, providing a fixed position for the Driver to rotate. The Driver Hub and the Driver rotate smoothly with respect to each other.
The Driver Hub has parallel slits in its structure, these slits run from mid point and progress forward ending approximately an inch from the edge of the Driver Hub. There is one slit above the axle hole and one slit below the axle hole. These slits are spaced apart relative to the diameter of the Converter hub. The Converter hub is primarily flat and is equal in diameter to the hole in the Center of the Converter. The one side-wall of the Converter facing away from the bicycle wheel is what contacts the Converter hub, providing a fixed position for the Converter to rotate. Ball The Converter Hub and the Converter rotate smoothly with respect to each other. The Converter hub is located on the inner side of the Driver hub facing the bicycle wheel. There is a slot in the center of the Converter hub equal to the diameter of the bicycle wheel axle. The slot begins at mid point and runs backwards ending approximately half and inch from the edge of the Converter hub.
Additional structures to the Converter hub are two cylindrical rods, one at the top of the Converter hub and one at the bottom. These rods are perpendicular to the Converter hub and attach to the same side. These small cylindrical rods approximately an inch in length fix the Converter Hub to the Driver Hub in concentric alignment via the slits in the Driver hub. These rods are passed through the slits and attach to the Shifter located on the outside of the Driver hub. The Shifter is a simple metal structure whose function is to slide the Converter hubxe2x80x94and the Converter rotating around itxe2x80x94forward by degrees, out of concentric alignment. The Shifter slides along the slits in the Driver Hub via manual manipulation by the bicycle rider, using a lever affixed to the handle bars and conventional cable tension used on current bicycles to pull the Shifter forward. Utilizing biasing members attached from the Shifter to the Driver Hub, the shifter returns to its original position and thus returning the Converter hub back to its original position in concentric alignment with the Driver hub.
The function of the Variable Ratio Sprocket Assembly is as follows, beginning with the first gear ratio, all the components are in concentric alignment, thus the torque delivered by the chain is transmitted equally from the Driver, to the Converter, to the Receiver and to the bicycle wheel. One rotation of the Driver equals one rotation of the Receiver/Transmitter, equals one rotation to the wheel. When the Shifter pulls the Converter hub and thus the Converter out of concentric alignment with the Driver and the Receiver, the unit behaves similar to a chain a two sprockets. The Driver is the first and larger sprocket, the Converter plays the role of the chain, and the Receiver is the second and smaller sprocket. The teeth of the Converter are in contact with increasing numbers of the stair-shaped ridges on the inner side-walls of the Driver, and the teeth of the Receiver are in contact with increasing numbers of the stair-shaped ridges on the inner side-walls of the Converter. Depending on the gear ratio selected, one rotation of the Driver equals a multiplied rotation ratio of the Converter, and one rotation of the Converter equals a multiplied rotation ratio of the Receiver, increasing torque to the wheel.
The function of the Stair-shaped ridges is to transmit torque when the leading edge is in contact with the flexing teeth, between the Driver and the Converter, and between the Converter and the Receiver. When the Converter is pulled out of concentric alignment with the Driver and the Receiver, a reduced number of Converter teeth come in alignment with the leading edge of the ridges on the inner side-walls of the Driver as the diameter increases. Likewise, a reduced number of Receiver teeth come in alignment with the leading edge of the ridges on the inner side-walls of the Converter as the diameter increases. Thus the flexing teeth of the Converter and the Receiver will squeeze in and slide along the trailing edge of the ridges, until the rotation brings the teeth into alignment with the leading edge of the ridges and torque is transmitted. When the teeth no longer align with the leading edge of the ridges as rotation progresses, the flexing teeth will again squeeze in and slide along the trailing edge of the ridges until they are liberated in the open space between the Driver and the Converter, and between the Converter and the Receiver. As rotation continues, the teeth return to make contact with the trailing edge of the ridges and will squeeze in and slide until the teeth align and are in contact with the leading edge of the ridges again where torque is transmitted. The leading edge transmits torque, while the trailing edge allows free rotation of flexing teeth when torque is reversed. In the case of the variable ratio sprocket assembly, increased rotational ratios and misalignment replace reversed torque to achieve slipping along the trailing edge of the ridges.
Regarding the structure of the Stair-shaped ridges. The leading edges of the ridges are parallel beginning from the smallest diameter and progressing to the largest diameter, for both the Driver and the Converter. The ridges do not taper outward as they reach the outer diameter, as this will not allow the flexing teeth to achieve true alignment when the Converter is shifted to the outer diameters. The ridges are designed in four quadrants; the four quadrants of ridges meet each other at right angles. The trailing edges of the ridges of a first quadrant will meet the leading edge of the next quadrant at right angles. This is repeated for each quadrant to form the ridge pattern. The increase in diameter increases the number of ridges per circumference. As the Converter shifts out of concentric alignment, the flexing teeth of the Converter and Receiver will receive torque from increased numbers of ridges of the increased circumferences between the Driver and the Converter, and between the Converter and the Receiver, and ratios are increased.
With this as an understanding of the theory of operation, the preferred embodiment will be described in detail.
Still yet another object of the present invention is to provide a new variable ratio sprocket assembly which provides in the apparatuses and methods of the prior art some of the advantages thereof, while simultaneously overcoming some of the disadvantages normally associated therewith.
Still another object of the present invention is to provide a new variable ratio sprocket assembly for providing improved transition between gears and eliminating derailing.
Yet another object of the present invention is to provide a new variable ratio sprocket assembly which includes an axle providing a center for rotation, a bicycle wheel hub coupled to a rear wheel of the bicycle and designed to rotatably receive force from the sprocket assembly, a receiver includes a first diameter coupled to the rear wheel hub such that rotating the receiver rotates the wheel, a converter includes a second diameter substantially greater than the diameter of the receiver and slideably engages the receiver to provide a plurality of gear ratios with respect to the receiver, a driver includes a third diameter substantially greater than the second diameter of the converter and is slideably engaged by the converter such that rotating the driver in a first direction rotates the converter in a first direction which in turn rotates the receiver in a first direction which rotates the rear wheel, and a sprocket coupled to an exterior surface of the driver designed for engaging a drive chain which rotates the sprocket.